Hair straightener



FIG. 1 is a perspective view of a hair straightener showing our new design;

FIG. 2 is a front elevation view of FIG. 1 ;

FIG. 3 is a rear elevation view of FIG. 1 ;

FIG. 4 is a left side elevation view of FIG. 1 ;

FIG. 5 is a right side elevation view of FIG. 1 ;

FIG. 6 is a top plan view of FIG. 1 ; and,

FIG. 7 is a bottom plan view of FIG. 1 .

The broken lines in the drawings depict portions of the hair straightener that form no part of the claimed design. 

CLAIM The ornamental design for a hair straightener, as shown and described. 